With Wednesday's release of Mac OS X Lion, Apple has definitively leapfrogged its rivals by offering an operating system with state-of-the-art security protections that make it more resistant to malware exploits and other hack attacks, two researchers say.
Unlike the introduction of Snow Leopard in 2009, which offered mostly incremental security enhancements, OS X 10.7 represents a major overhaul, said the researchers, who spent the past few months analyzing the OS.

The most important addition is full ASLR. Short for address space layout randomization, the protection makes it much harder for attackers to exploit bugs by regularly changing the memory location where shell code and other system components are loaded. Other improvements include security sandboxes that tightly restrict the way applications can interact with other parts of the operating system and full disk encryption that doesn't interfere with other OS features.